tests: Move 'riscvmatched-fs.py' example test to weekly

As of https://gem5-review.googlesource.com/c/public/gem5/+/64131, the
"configs/example/gem5_library/riscvmatched-fs.py' test was added to the
long/nightly test suite. This test is very long and the Nightly tests
are now timing out: https://jenkins.gem5.org/job/nightly/385/.

To solve this problem this test is being moved to the weekly tests.

Change-Id: I7956797b6ce1a813e1fdbbd38e8be61962d345a2
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/64671
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>

tests/gem5/gem5_library_example_tests/test_gem5_library_examples.py

@@ -322,5 +322,5 @@ gem5_verify_config(
     config_args=[],
     valid_isas=(constants.riscv_tag,),
     valid_hosts=constants.supported_hosts,
-    length=constants.long_tag,
+    length=constants.very_long_tag,
 )